Technical Abstract:
It has been proposed that a pure form of albuterol will deliver similar positive production effects without negative effects on well-being seen with other Beta-agonists. This experiment examined the effects of albuterol on behavior and heart rate (HR) during handling. The study used 192 pigs (88.8±0.9 kg BW) housed in groups of six in 32 pens (1.4m x 4.1m) and assigned to one of four treatments: 1) Control - standard finishing ration, 2) ALB-R2 - diet with 2 ppm of the pure R-enantiomer of albuterol, 3) ALB-R4 - diet with 4 ppm of pure R-albuterol, or 4) ALB-RS8 - diet with 8 ppm of a racemic mixture of R- and S-enantiomers. All diets supplied 18.3% CP, 1.1% lysine and 3534 kcal ME/kg and were offered ad libitum for a 4-wk period. Behavioral responses to handling during weighing were recorded immediately before assignment to the treatments (wk 0) and at weekly intervals over the subsequent 4-wk period (wk1-wk4). Behavioral and HR responses to a 10-min human presence test in the home pen were measured during wk 0, wk1 and wk3. Finally, HR responses to 5-min loading, 26-min transport and 5-min unloading periods were recorded. Data were analyzed using Proc GLM of SAS, with pen as the experimental unit. The treatment had no effect on overall handling measures (P>0.05), including the number of pigs exiting the pen voluntarily, the time taken to weigh, or the number of physical interactions needed by the handler to complete the task. Treatment also had no effect on behavioral responses to human presence (P>0.05), with all treatments willing to spend similar amounts of time close to, and interacting with the human. However, during the human presence test in wk1 and wk3, treated pigs had heart rates around 10 bpm higher (P<0.05) than control pigs. This was thought to be due to systemic vasodilation rather than direct Beta 1-receptor stimulation. During all phases of transport, heart rates were similar across treatments (P>0.05). The results indicate that albuterol-treated pigs do not differ markedly from control pigs in behavioral and heart rate responses to handling and transportation.